Unesterified neuroleptics within the phenothiazine, thioxanthene and butyrophenone series have for a long time been used in the treatment of psychoses including schizophrenia; and also esters of higher alkanoic acids of said neuroleptics having five or more carbon atoms in the chain have been suggested and also widely used in the form of solutions in oils, mostly sesame oil and light vegetable oil, which have a sustained action when administered parenterally, preferably intramuscularly, showing a depot effect for up to four weeks (see for example U.S. Pat. Nos. 3,194,733, 3,350,268 and 3,681,346 and British Pat. Nos. 833,473 and 1,186,973).
So far, however, only enanthates and decanoates of the neuroleptics in question have been commercially available.
There has been a need therefore for very long acting preparations having great stability at room temperature for up to two years.